1. Field of the Invention
The present invention relates to a linear motor compressor, and in particular to an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum condition.
2. Description of the Prior Art
Generally, by eliminating the use of a crankshaft for converting a rotary motion into a linear motion, a linear motor compressor has a low frictional loss, and accordingly the linear motor compressor is superior to a general compressor in the compressing efficiency aspect.
When the linear motor compressor is used for a refrigerator or an air conditioner, a cooling capacity of the refrigerator or the air conditioner can be controlled by varying a compression ratio of the linear motor compressor by varying a stroke voltage applied to the linear motor compressor. The linear motor compressor will be described with reference to accompanying FIG. 1.
FIG. 1 is a schematic block diagram illustrating the construction of an apparatus for controlling the operation of a linear motor compressor in accordance with the prior art.
As depicted in FIG. 1, the apparatus for controlling the operation of a linear motor compressor in accordance with the prior art applies a stroke voltage to an internal motor (not shown) of a linear motor compressor 13 for varying an internal stroke supplied according to a stroke reference value set by a user, thereby adjusting a cooling capacity by moving an internal piston (not shown) back and forth. A voltage detecting unit 14 detects a voltage generated in the linear motor compressor 13 according to the variation of the stroke, and a current detecting unit 12 detects a current generated in the linear motor compressor 13 according to the variation of the stroke. A microcomputer 15 calculates the stroke by using the voltage detected by the voltage detecting unit 14 and the current detected from the current detecting unit 12, comparing the calculated stroke with the stroke reference value and outputting a switching control signal according to the comparison result. And a power supply unit 11 supplies the stroke voltage to the linear motor compressor 13 by on-off controlling the supplying of AC power to the linear motor compressor 13 using a triac Tr1 controlled by the switching control signal from the micro-computer 15. Hereinafter, the operation of the apparatus for controlling the operation of the linear motor compressor will be described.
First, the stroke of the linear motor compressor 13 is varied in accordance with the voltage supplied to the motor according to the stroke reference value, and thereby adjusts the cooling capacity by moving the piston back and forth according to the varied stroke. Herein, the term xe2x80x9cstrokexe2x80x9d means a distance over which the piston inside the linear motor compressor 13 moves while performing a reciprocating motion (moving back and forth).
When the triac Tr1 of the power supply unit 11 has a longer turn-on duration in accordance with the switching control signal outputted from the microcomputer 15, at this time the AC turn-on power is supplied to the linear motor compressor 13, and the linear motor compressor 31 operates. Herein, the voltage detecting unit 14 and the current detecting unit 12 respectively detect a voltage and a current applied to the linear motor compressor 13 and respectively output the detected voltage and current to the microcomputer 15.
The microcomputer 15 calculates the stroke by using the voltage and the current detected from the voltage detecting unit 14 and the current detecting unit 12, compares the calculated stroke with the stroke reference value and outputs the switching control signal according to the comparison result. In more detail, when the calculated stroke value is smaller than the stroke reference value, the microcomputer 15 increases the stroke voltage supplied to the linear motor compressor 13 by outputting a switching control signal for lengthening the turn-on cycle of the triac Tr1 in the power supply unit 11.
On the contrary, when the calculated stroke value is larger than the stroke reference value, the microcomputer 15 decreases the stroke voltage supplied to the linear motor compressor 13 by outputting a switching control signal for shortening the turn-on cycle of the power supply unit 11.
However, because the linear motor compressor control apparatus according to the prior art controls the operation of the linear motor compressor by comparing the calculated stroke with the stroke reference value and outputting a switching control signal to the power supply unit according to the comparison result, accordingly the operation of the linear motor compressor can not be controlled accurately. In more detail, since the linear motor compressor control apparatus according to the prior art has a severe non-linearity in its mechanical motion functions, the operation of the linear motor compressor can not be performed precisely and accurately by a linear control method without considering the non-linearity.
In addition, in the linear motor compressor control apparatus according to the prior art, when the linear motor compressor is operated continually in accordance with an initial detected switching control signal, a position of the piston may deviate from TDC (Top Dead Center)=0 due to a load variation according to changes in a refrigerator and other circumstances.
Accordingly, it is an object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a linear motor compressor precisely and accurately by detecting a peak value of a current waveform generated in a linear motor compressor, recognizing the peak value of the current waveform as a point TDC=0 and operating the linear motor compressor according to a duty-ratio corresponding to maintaining the point TDC =0.
It is another object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a refrigerator efficiently by detecting a current peak value in an optimum operation condition as TDC=0 when the load varies due to changes in a refrigerator and the operating circumstances, recognizing the detected peak value of the current waveform as a position in TDC=0 and operating a linear motor compressor according to a duty-ratio corresponding to maintaining the recognized point TDC=0.
It is yet another object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a refrigerator efficiently by periodically detecting a current peak value as TDC=0 when a load change according to changes in a refrigerator and the operating circumstances, recognizing the detected peak value of the current waveform as a position TDC=0 and operating the linear motor compressor according to a duty-ratio corresponding to maintaining the recognized point TDC=0.
It is still another object of the present invention to provide an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum operation condition by detecting load variation due to changes in a refrigerator and the circumstances with a quantity of power consumption, comparing the quantity of power consumption with a maximum power quantity and a minimum power quantity and detecting a current peak value in TDC= according to the comparison result.
It is yet still another object of the present invention to provide an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum condition by checking load variation of a refrigerator with current variation by using currents generated in a linear motor compressor.
In order to achieve the above-mentioned objects, an apparatus for controlling operation of a linear motor compressor in accordance with the present invention includes a current detecting unit detecting a current generated in a linear motor compressor, a current peak value detecting unit detecting a current peak value by comparing the detected current with a formerly detected current, a microcomputer recognizing the current peak value as a point of TDC=0 and outputting a switching control signal according to a duty-ratio corresponding to the point of TDC=0, and a power supply unit operating the linear motor compressor by controlling operation of an internal triac according to the switching control signal.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes detecting an initial current peak value as TDC (Top Dead Center)=0 on the basis of currents supplied to a linear motor compressor, setting a limitation value at a point of detecting the initial current peak value, and redetecting a current peak value as TDC=0 by comparing the current value generated in the linear motor compressor with the limitation value.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes detecting an initial current peak value as TDC=0 by comparing a current applied to a linear motor compressor with a formerly detected current, setting a certain time period for redetecting an optimum operation condition as TDC=0 on the basis of a time of detecting the initial current peak value, judging whether the certain time period is passed while operating the linear motor compressor with a switching control signal corresponding to the initial current peak value, and redetecting a current peak value as TDC=0 after the certain time period is passed and operating the linear motor compressor with a switching control signal corresponding to the re-detected current peak value.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes detecting a current peak value as TDC=0 by comparing a current applied to a linear motor compressor with a formerly detected current, setting a maximum current value for redetecting an optimum operation condition at TDC=0 on the basis of the detected current peak value, operating the linear motor compressor with a switching control signal corresponding to the detected current peak value and at the same time comparing a first current value applied to the linear motor compressor with the set maximum current value, and detecting a current peak value at TDC=0 when the first current value is larger than the set maximum current value.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes detecting an initial current peak value at TDC=0, detecting a quantity of power consumption on the basis of a current and a voltage generated in the linear motor compressor, setting a minimum power quantity and a maximum power quantity on the basis of the detected current and voltage, and operating the linear motor compressor by a switching control signal corresponding to the initial current peak value, while at the same time comparing the quantity of power consumption with the maximum power quantity and the minimum power quantity and controlling the operation of the linear motor compressor according to the comparison result.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes detecting an initial current peak value as TDC=0 by comparing a current applied to a linear motor compressor with a formerly detected current, setting a redetecting time period for detecting a current peak value as TDC=0 on the basis of a detecting time point of the initial current peak value, judging whether the set redetecting time period is passed and at the same time operating the linear motor compressor with a switching control signal corresponding to the initial current peak value, and redetecting a current peak value as TDC=0 and controlling the operation of the linear motor compressor with a switching control signal corresponding to the detected current peak value.
A method for controlling operation of a linear motor compressor in accordance with the present invention includes judging whether a flag for detecting a duty-ratio of a driving current of a linear motor compressor is set, judging whether a peak value of a current waveform driving the linear motor compressor a duty-ratio corresponding to the peak value of the current waveform is not greater than a certain value, detecting a peak value of the driving current waveform and generating a switching control signal according to a duty-ratio corresponding to the detected peak value when the peak value of the current waveform and the duty-ratio are not greater than the certain value, and operating the linear motor compressor according to the switching control signal.